Introduction: Recently, a post stating that "covering watermelon with plastic wrap before refrigerating it actually leads to more bacteria than not using it" has been widely shared by netizens. Some netizens were shocked: "From watermelon sellers to myself, this is how we've always done it. Could we have been wrong all along?"
Experiments have proven that watermelon wrapped in plastic spoil faster than unwrapped watermelon. This is because before being covered, the surface of the watermelon already has bacteria and microorganisms. If the plastic wrap has poor breathability and moisture permeability, and the temperature drops slowly, it will cause these microorganisms or bacteria to multiply faster. Especially after an anaerobic reaction occurs, the food can easily spoil.
Nutrient changes when using plastic wrap
Nowadays, people's reliance on plastic wrap is growing stronger. For vegetables, fruits, and leftovers, just covering them with it provides much peace of mind. Recently, some research has pointed out that not all foods are suitable for plastic wrap. This is especially true for some fruits and vegetables that naturally release ripening gases, such as tomatoes and bananas. Using plastic wrap on them hinders the release of ethylene gas that promotes ripening, thereby shortening their shelf life. Only fruits and vegetables with high moisture content are suitable for preservation with plastic wrap. For apples, pears, bok choy, and yellow chives, using plastic wrap not only preserves them for a longer time but can also increase some of their nutrients.
Experiments show that in 100 grams of yellow chives wrapped in plastic wrap, the vitamin C content after 24 hours is 1.33 mg more than when unwrapped. For bok choy and lettuce leaves, it is 1.92 mg more. However, the experimental results for some vegetables were vastly different. After one day, 100 grams of radish wrapped in plastic wrap had 3.4 mg less vitamin C; beans lost 3.8 mg; and after one day and night, the amount of vitamin C lost from a cucumber was equivalent to that in 5 apples.
It is not advisable to use plastic wrap for storing meat
If the plastic wrap is too thick, it can prevent the food from breathing oxygen, leading to anaerobic fermentation and spoilage. It should be noted that some people think that an extra layer of sealing preserves food better, but plastic wrap must not only keep moisture from evaporating but also allow carbon dioxide to escape. A wrap that is too thick is actually detrimental to preservation.
It is best not to use plastic wrap to package and store cooked food, hot food, or oily food, especially meat. Plasticizers in the plastic wrap can easily leach out at high temperatures and enter the food's oils, then be absorbed by the human body. If plasticizers accumulate in the body over the long term, their toxicity is far higher than that of melamine. They can cause hormonal imbalances, a decrease in human immunity, and most importantly, affect reproductive ability. They may lead to issues such as underdeveloped genitalia and indistinct secondary sexual characteristics, and can also trigger precocious puberty in children.